Solve "Index exceeds the number of array elements (1)", "Vectors must be the same length." errors
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sookyung Kang
il 15 Lug 2020
Commentato: Walter Roberson
il 20 Lug 2020
I'd like to solve those problems from under coding using A, B, and C relationships. If equation error can't be fixed, "B(i+1)=B(i)+((h.*q)/(k*T*E))*C(i)" can be used.
a = 0;
b = 1;
n = 110;
k = 8.61733*10^(-5);
T = 300 ;
q = 1.60218*10^(-19);
E = 8.8542*10^(-12)
x= linspace(a,b,n);
h= x(2)-x(1);
A = zeros(size(x));
B = zeros(size(x));
for i = 0:n-1
A(0)=3;
B(0)=1;
C(i)=2*x(i)+3;
A(i+1)=A(i)-h.*B(i)-(0.5.*h.^2*q.*C(i))./(k*T*E);
B(i+1)=B(i)+((h.*q)/(k*T*E))*0.5*(C(i)+C(i+1));%equation error
end
plot(transpose(x),A,'.')
1 Commento
Tanmay Das
il 15 Lug 2020
Hi. Can you please try starting the index from 1 instead of 0 and go upto n in the for loop?
Risposta accettata
Walter Roberson
il 15 Lug 2020
a = 0;
b = 1;
n = 110;
k = 8.61733*10^(-5);
T = 300 ;
q = 1.60218*10^(-19);
E = 8.8542*10^(-12)
x= linspace(a,b,n);
h= x(2)-x(1);
A = zeros(size(x));
B = zeros(size(x));
A(0+1)=3;
B(0+1)=1;
for i = 0:n-1
C(i+1)=2*x(i+1)+3;
A(i+1+1)=A(i+1)-h.*B(i+1)-(0.5.*h.^2*q.*C(i+1))./(k*T*E);
B(i+1+1)=B(i+1)+((h.*q)/(k*T*E))*0.5*(C(i+1)+C(i+1+1));
end
plot(transpose(x),A,'.')
12 Commenti
Walter Roberson
il 20 Lug 2020
Which theoretical equation are you comparing to, and which result from your program are you comparing it to?
How do you know when you have reached and adequate solution?
Più risposte (1)
Tanmay Das
il 15 Lug 2020
Hi,
I have the understanding that you are facing trouble in indexing of arrays. Unlike C++ or Python, indexing starts from 1 in MATLAB. So if you write A(0), then it will throw error. The following code may be useful for your understanding:
a = 0;
b = 1;
n = 110;
k = 8.61733*10^(-5);
T = 300 ;
q = 1.60218*10^(-19);
E = 8.8542*10^(-12)
x= linspace(a,b,n);
h= x(2)-x(1);
A = zeros(size(x));
B = zeros(size(x));
A(1)=3;
B(1)=1;
C = 2*x + 3
for i = 1:n-1
A(i+1)=A(i)-h.*B(i)-(0.5.*h.^2*q.*C(i))./(k*T*E);
B(i+1)=B(i)+((h.*q)/(k*T*E))*0.5*(C(i)+C(i+1));%equation error
end
plot(transpose(x),A,'.')
Also please note that similar operations on each element of array can be done at once in MATLAB and do not require to run a loop like in case of C.
C = 2*x + 3
Hope that helps!
1 Commento
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